Long distance pumping

Pumping concrete while protecting the environment

A unique task for Putzmeister: a pump is currently delivering concrete along a pipeline across the Spreewald biosphere reserve to a construction site 450 m away. The installation of a sluice was designed to overcome the difference in level of the watercourse. The successful progress of this project has shown that nature conservation and concrete pumps can go hand in hand.

The Spreewald in Brandenburg is an area of significant touristic interest located approximately 70 km away from Berlin. In addition to many other free-time activities, travelling along the endless stretches of water in all types of vessel is a popular activity. Plans are in place to install a new sluice at a location with limited access before the 2013 summer season to overcome the difference in height and allow river enthusiasts to continue enjoying their journey undisturbed. It is not only the extremely tight schedule restricting construction to a total of nine months and the predominantly wintry conditions during this period that pose a major challenge. Right from the start, the project team had to concentrate their efforts on the logistics across an almost impenetrable landscape. Know-how, teamwork and outstanding technical equipment were required to overcome this hurdle.

First hurdle – Construction site with limited access in a conservation area

The relevant sluice (number 112) is located in a biosphere reserve at the heart of the Spreewald far away from any paved roads and surrounded by a marshy, almost impenetrable landscape. Heavy construction vehicles can only reach as far as the car park of a nearby restaurant and must travel another 450 m to reach the construction site.

As early as January 2012, the project team began to discuss and test different methods of transporting concrete and other building materials to the construction site using environmentally friendly means. For a brief moment, transportation by donkey was a serious consideration. The engineering company PTW (Planungsgemeinschaft Tief- und Wasserbau GmbH) based in Dresden contacted and included the project engineers from Putzmeister in the project at an early stage. Consequently, a stable concrete conveying concept with minimum environmental impact was developed within a very short time. The concrete had to be transported to the exact location along a pipeline laid across the protected landscape without any kind of manual intervention. In terms of nature conservation, the concept stipulates that the concrete pump and pipeline must be cleaned in such a way that no concrete residues or washing water is deposited into the Spreewald. The practical solution: cleaning forwards using compressed air to convey the concrete residues into the formwork.

Second hurdle – Testing the pumpability of the concrete recipe

It was initially unclear whether the pump would be suitable for conveying the specified concrete recipe over a distance of 450 m. Qualified personnel conducted tests on the floor concrete C30/37 at the company headquarters of Kann Beton in Koschendorf, Germany using a SLIPER rheometer. This measuring device provides values that indicate the expected conveying resistance (friction value) of concrete in the delivery line. It is then possible to draw conclusions about the concrete pump and pipeline required for the job. If the results of the measurement are positive, the selected concrete pump can be approved for operation.

Work to set up the construction site began in November 2012. The companies involved transported sheet piling and other materials to the construction site on flat barges. Floating pontoons were used to transport the excavators. Putzmeister project engineers were responsible for installing, setting up and securing the pipeline in close collaboration with all the companies involved in the concreting process. They made all the necessary preparations, in particular for cleaning work and possible emergencies during concreting (blockages). Workers secured the pipeline at several points in anticipation of the high delivery pressures of almost 100 bar.

Third hurdle – Adverse weather conditions

Work on concreting the floor of the sluice began at the end of March 2013. In spite of snow storms and subzero temperatures, the pump seamlessly conveyed the concrete into the first 150 m3 of formwork. The concrete pump service provider TBG Pumpendienst Berlin appointed to the task used a MOLI truck-mounted concrete pump from Putzmeister. The truck is equipped with a powerful concrete pump designed for delivery pressures up to 115 bar.

Preparations, on-site specialists and excellent equipment paved the way for the timely completion of the construction work.